1. Field of the Invention
The present invention relates to a medical thrust device such as an indwelling device or a syringe which is designed to subcutaneously its needle into the blood vessel or bile duct for injection or removal of blood or body fluids, and more particularly to a disposal medical device which is intended to be used once and then thrown away, thereby guaranteed to be free of contagion by injuring one's hand with the blood-smeared or bacilli-contaminated needle.
2. Description of Related Art
Such a disposal medical device includes a hard metal needle. A used needle is smeared with blood or body flood, which contains bacilli. Lest people should be infected with such bacilli, the blood-smeared needle body is used once and then thrown away. The precaution must be taken against every possible infection to doctors, nurses, assistants and collectors of waste materials. Therefore, the used needles must be contained in disposable casings, and advantageously the needle casings from which the needles are taken out are reused as such disposable casings.
Once a used needle has been put in its casing there will be no fear for infection. When the used needle is being put in the casing with one hand holding the used needle and with the other hand holding the casing, the person often injures his hand with the sharp point of the bacilli-contaminated needle.
In an attempt to prevent this dangerous incident, an indwelling device has been designed to have a needle cover responsive to removal of the needle from the spot for automatically covering its sharp point, as for instance in Japanese Patent 3-191965(A). Specifically, the needle cover is in the form of expandable-and-shrinkable (telescoping or coiled-spring) body, and it has a cap on its top end, and its bottom end is attached to the hub of the needle, and the cap is fixed to the hub of the surrounding cannula. The sharp point of the needle is allowed to appear from the cannula by shrinking the expandable-and-shrinkable body, and then the needle is thrusted into a selected part of the human body. As the needle is removed from the spot, the expandable-and-shrinkable body is allowed to expand so that the cap may cover the sharp point of the needle upon complete removal of the needle from the indwelling cannula.
The expandable-and-shrinkable body is maintained in the shrinking position only by the friction between the expandable-and-shrinkable body and the surrounding cannula, and also by the friction between the needle and the surrounding expandable-and-shrinkable body, and therefore, once the expandable-and-shrinkable body has been put in the shrinking position it may be possible to allow the expandable-and-shrinkable body along with the surrounding cannula to extend beyond the sharp point of the needle before or during rather than removal from the thrust spot. Thus, extra caution is required in use.
The expandable-and-shrinkable body must be long enough to cover the full length of the needle when it extends to its full length, and therefore, the radial size of the expandable-and-shrinkable body of telescoping type will be large. In case that the needle has a relatively long length, the outer radial size of the telescoping body when shrinked will be inhibitably large, radially extending a substantial size beyond the radial size of the cannula, thus causing an inconvenience in thrusting the needle into a selected part of the human body.
Further, there has been proposed an injection needle storing container designed to have a long pore having a broad part and a narrow part on a cover plate of the container for removing a injection needle from a syringe body by hooking the needle hub with the pore, for instance in Japanese Patent 1-52480(A) and 1-136665(A). A used injection needle is inserted into the broad part of the pore and shifted to the narrow part keeping a flange of the needle hub lower side of the cover plate and the syringe body is shifted upward to drop and store the separated injection needle into the container.
However, the used injection is exposed without cover before disposing into the container and accordingly it is not enough to guarantee to be free from infection. Also, it is afraid that long term storing may cause an accident to fall the container and the stored needles spring out of the hole.
Therefore, there has been an ever increasing demand for a disposal medical device guaranteed to be free of injuring one's hand with the bacilli-contaminated needle, still assuring that it can be handled with ease.